1. Field of the Invention
This invention relates to air-tight stoves and, in particular, to an improved air-tight stove having means for adjusting chimney air flow and temperature in response to an adjustment in stove adding to and maintaining proper chimney air flow and temperature when the stove's combustion inlet flow is reduced, thereby reducing the accumulation of creosote and other materials in the chimney greatly reducing the possiblity of chimney fires. It also relates to a method of achieving such proper chimney flow.
2. Description of the Prior Art
Wood burning stoves have recently surged in popularity and use due in large measure to the rising costs of conventional fuels. Air-tight wood stoves are one of the most useful types of stoves because of their ability to regulate and control air flow into the stove's combustion chamber. However, when air flow is reduced for extended periods, for example overnight, to slow down combustion rates, the concommitant reduction in the flow of hot chimney air allows combustable residue, most notably creosote, to build up especially in the chimney walls. Unfortunately, this residue is the source and most prevalent cause of chimney fires.
The need to prevent the buildup of combustable materials on chimney walls has long been recognized in the prior art. For example, U.S. Pat. No. 692,164 to Miller describes heating and ventilating apparatus for furnishing fresh air to be heated and for carrying off stagnant air, the apparatus including an outer casing for the heating stove wherein the fresh, outside air is heated to a suitable temperature prior to being introduced into the chimney flue. The freshly heated air is fed to the chimney at a point below that where the stove exhaust is introduced into the chimney flue. The freshly heated air is fed to the chimney at a point below that where the stove exhaust is introduced. Also of interest is the apparatus described by Belvin in U.S. Pat. No. 891,900, by Harr in U.S. Pat. No. 907,044 and by Street in U.S. Pat. No. 1,439,925. Each of these prior art arrangements illustrate ventilation apparatus for heating systems wherein fresh and/or stale air is used to supplement normal chimney flow. However, none of the above was concerned with the buildup of creosote or other combustible materials on the chimney walls.
In U.s. Pat. No. 1,967,128 to Moser, a ventilator device intended to prevent creosote buildup in a chimney is described. This apparatus relies on an auxiliary air flow supply pipe having an independent concavo-convex damper inserted at the intake end thereof. This damper is adapted to be regulated by wind induced draft to insure chimney flow and thereby hopefully prevent creosote buildup when the stove is banked. The auxiliary air flow is not directly heated by the stove in the Moser apparatus. A similar intent to prevent soot and creosote buildup is evidenced by the apparatus shown in U.S. Pat. No. 2,072,758 by Libby wherein a dual-baffle device is inserted in a chimney below the entry point of the stove exhaust pipe. The baffle is designed to prevent buildup in the flue below that entry point. This arrangement does not utilize an auxiliary air flow.
Unfortunately, the several prior art arrangements all fail to fully compensate for reduced air flow when the stove is banked and/or do not provide a source of warmed auxiliary air to prevent soot and creosote buildup in the chimney flue. It should be noted that a flow of cold or even room temperature air will not prevent exhaust gas condensation and subsequent buildup in the flue since lower exhaust gas temperatures tend to promote condensation of the gases.